By David Willey
BBC correspondent in Florence
Exactly 500 years after Michelangelo carved his monumental statue of David out of a single block of Carrara marble, the artwork has just undergone the most thorough and careful cleaning in its history.
The huge naked figure of David, over five metres high - nearly three times life-size - stands on a new plinth in the Accademia Gallery under a small glass dome, created to allow visitors to view the Renaissance artist's creation lit from every angle.
The muscles ripple across his torso.
The tension of this idealised male body communicates itself to every visitor.
The statue has become one of the major icons of Western art.
It was brought inside the gallery to protect it from the weather towards the end of the 19th Century.
"Unless this had been done, city pollution would have caused terrible damage to the marble," Franca Falletti, director of the gallery told BBC News.
This was how the statue looked before its clean-up
Walking through the centre of Florence on the way to the gallery, you notice the streaks of dirt which already disfigured and marred the brilliantly coloured marble facade of Florence's Cathedral, the Duomo, despite its cleaning and restoration 10 years ago.
'Faced with genius'
The cleaning of David was carried out by restorer Cinzia Parnigoni, using very simple techniques - basically washing every part of the statue very carefully with swabs dipped in distilled water.
"Face-to-face every day with Michelangelo's sculpture, I knew I was in the presence of his genius," she said.
"Michelangelo knew that the block of marble he chose had already been rejected by two other Florentine artists because it was defective.
"It was full of veins and holes. This would have presented a real problem to any sculptor. It meant that it could break at any minute under his chisel. Michelangelo could not afford to make a single mistake."
The cleaning has been financed partly by the Italian taxpayer, partly by art lovers in the Netherlands and in America.
Willem Dreesman, president of the Dutch Ars Longa Foundation said his fund had contributed over $200,000 (£110,800) towards the cost.
"Ten years ago I discovered that the statue had not been properly cleaned for over a century. No-one had done any maintenance. It's minimal maintenance it needs, just like I take a shower," Mr Dreesman said.
The statue has survived several attacks, including one during a city riot in Michelangelo's own lifetime when one of its arms was smashed and then repaired.
Another took place only 10 years ago when a deranged man smashed one of David's feet with a hammer.
Cristina Acidini, a Florentine art historian said: "This man entered the gallery with a hammer hidden under his coat. He jumped up and hit the big toe, shattering it, before he could be restrained by security guards.
"That incident however did mark the beginning of the scientific research which preceded the now completed restoration. The fragments of marble which fell off were sent for analysis."
Later this week, crowds of tourists are expected to return to admire the David just like the Florentines did when it was first unveiled here 500 years ago.
Researchers say a Florentine goldsmith was paid by Michelangelo to supply what was described as "a garland of gilded copper" to hide the naked figure's private parts.
There is no evidence that the "garland" was ever placed on the statue, but during most of the 19th Century David's genitals were covered by a stucco fig leaf .
Now in the 21st Century, public taste has turned full circle and a cover-up of David's nakedness is no longer considered necessary by the director of the Accademia Gallery.
Curiously, however, the fig leaf has returned on certain commercial reproductions.